Medical device communication and charging assemblies for use with implantable signal generators, and associated systems and methods

ABSTRACT

Communication and charging assemblies for medical devices are disclosed herein. A communication and charging assembly in accordance with a particular embodiment includes a support element, with a communication antenna and a charging coil coupled to the support element. The charging coil can include wire loops having a plurality of wires and the support element can include a mounting surface shaped to match the charging coil and the communication antenna. In one embodiment, the communication and charging assembly are mounted in a header of an implantable signal generator.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to U.S. Provisional Application61/556,097, filed Nov. 4, 2011, and titled MEDICAL DEVICE COMMUNICATIONAND CHARGING ASSEMBLIES FOR USE WITH IMPLANTABLE PULSE GENERATORS, ANDASSOCIATED SYSTEMS AND METHODS, the entirety of which is incorporated byreference herein. To the extent the foregoing application and/or anyother materials incorporated herein by reference conflict with thepresent disclosure, the present disclosure controls.

TECHNICAL FIELD

The present technology is directed generally to communication andcharging assemblies for medical devices, and associated systems andmethods. Communication antennas in accordance with the presenttechnology are suitable for transmitting and receiving communicationsbetween medical device components, including communications between animplantable signal generator of a neurological stimulation system andexternal medical devices. Charging coils in accordance with the presenttechnology are suitable for charging medical devices, includingimplantable signal generators.

BACKGROUND

Neurological stimulators have been developed to treat pain, movementdisorders, functional disorders, spasticity, cancer, cardiac disorders,and various other medical conditions. Implantable neurologicalstimulation systems generally have an implantable signal generator(sometimes referred to as an “implantable pulse generator” or “IPG”)that is operably coupled to one or more leads that deliver electricalsignals or pulses to neurological tissue or muscle tissue. For example,several neurological stimulation systems for spinal cord stimulation(SCS) have cylindrical leads that include a lead body with a circularcross-sectional shape and multiple conductive rings spaced apart fromeach other at the distal end of the lead body. The conductive ringsoperate as individual electrodes or contacts to deliver electricalsignals to the patient. The SCS leads are typically implanted eithersurgically or percutaneously through a needle inserted into the epiduralspace, often with the assistance of a stylet.

Once implanted, the signal generator applies electrical signals to theelectrodes, which in turn modify the function of the patient's nervoussystem, such as by altering the patient's responsiveness to sensorystimuli and/or altering the patient's motor-circuit output. Inparticular, the electrical signals can generate sensations that mask orotherwise alter the patient's sensation of pain. For example, in manycases, patients report a tingling or paresthesia that is perceived asmore pleasant and/or less uncomfortable than the underlying painsensation. In other cases, the patients can report pain relief withoutparesthesia or other sensations. As used herein, unless explicitlystated otherwise, the terms “pulses” and “signals” are usedinterchangeably to include any waveform shapes, whether continuous ordiscontinuous, including but not limited to sinusoidal or non-sinusoidalwaves such as square waves, triangle waves, sawtooth waves, etc.

The implantable signal generator generally includes a communicationantenna that allows operational parameters of the stimulation system tobe altered, without necessitating a hard wired external connection.Implantable signal generators often include a charging coil that allowsa battery in the implantable signal generator to be recharged from anexternal power source. The design of the communication antenna and thecharging coil, and their locations within the implantable signalgenerator, can significantly impact the performance of the stimulationsystem. If the antenna and/or the coil are poorly positioned orshielded, updating operational parameters and/or charging theimplantable signal generator can be difficult or impossible. Forexample, in many existing systems it can be difficult for a patient oran operator to correctly position an external device to transmit signalsto the implantable signal generator. Additionally, poor coil design orshielding interference can decrease the efficiency of the chargingprocess and cause increased heating. Prior systems suffer from many ofthese and/or additional drawbacks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic illustration of an implantable spinalcord modulation system positioned at a patient's spine to delivertherapeutic signals in accordance with an embodiment of the presenttechnology.

FIG. 2 is a partially schematic isometric view of an implantable signalgenerator having a header and a can configured in accordance with afurther embodiment of the present technology.

FIG. 3 is an isometric view of a charging coil having a pair of wireloops in accordance with another embodiment of the present technology.

FIG. 4 is an isometric view of a communication antenna having curvedconnectors configured in accordance with a further embodiment of thepresent technology.

FIG. 5 is an isometric view of a support element having a firstreceiving surface and a second receiving surface in accordance withanother embodiment of the present technology.

FIG. 6 is an isometric view of a charging and communication assemblyhaving a communication antenna and a charging coil in accordance with anembodiment of the present technology.

FIG. 7 is an isometric view of a portion of an implantable signalgenerator having a header configured in accordance with a furtherembodiment of the present technology.

FIGS. 8A-8D schematically illustrate charging coils configured inaccordance with other embodiments of the present technology.

FIG. 9 is a partially cutaway side view of a portion of an implantablesignal generator having a header configured in accordance with a furtherembodiment of the present technology.

FIG. 10 is a cross-sectional end view of a portion of an implantablesignal generator configured in accordance with an embodiment of thepresent technology.

FIGS. 11A and 11B are isometric views of implantable signal generatorsconfigured in accordance with embodiments of the present technology.

FIG. 12 is an isometric view of a pre-molded header cap configured inaccordance with an embodiment of the present technology.

DETAILED DESCRIPTION

The present technology is directed generally to communication andcharging assemblies for medical devices, and more specifically tocommunication and charging assemblies for implantable neurologicalmodulation systems. At least some embodiments of the present technologyinclude implantable signal generators having communication antennasand/or charging coils in a header of the signal generator. Thecommunication antennas can be constructed, shaped and positioned invarious manners to provide improved, enhanced, more robust and/or moreeffective signal reception and/or generation. The charging coils can beconstructed, shaped and positioned to enhance charging efficiency anddecrease heat generation. In other embodiments, the devices, systems andassociated methods can have different configurations, components, and/orprocedures. Still other embodiments may eliminate particular componentsand/or procedures. The present technology, which includes associateddevices, systems, and procedures, may include other embodiments withadditional elements or steps, and/or may include other embodimentswithout several of the features or steps shown and described below withreference to FIGS. 1-12. Several aspects of overall systems configuredin accordance with the disclosed technology are described with referenceto FIG. 1, and features specific to particular communication andcharging assemblies are then discussed with reference to FIGS. 2-12.

FIG. 1 schematically illustrates a representative patient system 100 forproviding relief from chronic pain and/or other conditions, arrangedrelative to the general anatomy of a patient's spinal cord 191. Theoverall patient system 100 can include a signal delivery device 110,which may be implanted within a patient 190, typically at or near thepatient's spinal cord midline 189, and coupled to a signal generator 101(e.g., a pulse generator). The signal delivery device 110 carriesfeatures for delivering therapy to the patient 190 after implantation.The signal generator 101 can be connected directly to the signaldelivery device 110, or it can be coupled to the signal delivery device110 via a signal link or lead extension 102. In a further representativeembodiment, the signal delivery device 110 can include one or moreelongated lead(s) or lead body or bodies 111. As used herein, the terms“lead” and “lead body” include any of a number of suitable substratesand/or support members that carry devices for providing therapy signalsto the patient 190. For example, the lead or leads 111 can include oneor more electrodes or electrical contacts that direct electrical signalsinto the patient's tissue, such as to provide for patient pain relief.In other embodiments, the signal delivery device 110 can includestructures other than a lead body (e.g., a paddle) that also directelectrical signals and/or other types of signals to the patient 190.

The signal generator 101 can transmit signals (e.g., electrical signalsor therapy signals) to the signal delivery device 110 that up-regulate(e.g., stimulate or excite) and/or down-regulate (e.g., block orsuppress) target nerves. As used herein, and unless otherwise noted, to“modulate” or provide “modulation” to the target nerves refers generallyto having either type of the foregoing effects on the target nerves. Thesignal generator 101 can include a machine-readable (e.g.,computer-readable) medium containing instructions for generating andtransmitting suitable therapy signals. The signal generator 101 and/orother elements of the system 100 can include one or more processor(s)107, memory unit(s) 108 and/or input/output device(s) (not shown).Accordingly, the process of providing therapy signals, providingguidance information for positioning the signal delivery device(s) 110,and/or executing other associated functions can be performed bycomputer-executable instructions contained by computer-readable medialocated at the signal generator 101 and/or other system components. Thesignal generator 101 can include multiple portions, elements, and/orsubsystems (e.g., for directing signals in accordance with multiplesignal delivery parameters), carried in a single housing, as shown inFIG. 1, or in multiple housings.

In some embodiments, the signal generator 101 can obtain power togenerate the therapy signals from an external power source 103. Theexternal power source 103 can transmit power to the implanted signalgenerator 101 using electromagnetic induction (e.g., RF signals). Forexample, the external power source 103 can include an external coil 104that communicates with a corresponding internal coil (not shown) withinthe implantable pulse generator 101. The external power source 103 canbe portable for ease of use.

During at least some procedures, an external stimulator or trialmodulator 105 can be coupled to the signal delivery device 110 during aninitial procedure, prior to implanting the signal generator 101. Forexample, a practitioner (e.g., a physician and/or a companyrepresentative) can use the trial modulator 105 to vary the therapyparameters provided to the signal delivery device 110 in real time, andselect optimal or particularly efficacious parameters. These parameterscan include the location from which the electrical signals are emitted,as well as the characteristics of the electrical signals provided to thesignal delivery device 110. In a typical process, the practitioner usesa cable assembly 120 to temporarily connect the trial modulator 105 tothe signal delivery device 110. The practitioner can test the efficacyof the signal delivery device 110 in an initial position. Thepractitioner can then disconnect the cable assembly 120 (e.g., at aconnector 122), reposition the signal delivery device 110, and reapplythe electrical therapy. This process can be performed iteratively untilthe practitioner obtains the desired position for the signal deliverydevice 110. Optionally, the practitioner may move the partiallyimplanted signal delivery element 110 without disconnecting the cableassembly 120. Furthermore, in some embodiments, the iterative process ofrepositioning the signal delivery device 110 and/or varying the therapyparameters may not be performed.

After a trial period with the trial modulator 105, the practitioner canimplant the implantable signal generator 101 within the patient 190 forlonger term treatment. The signal delivery parameters provided by thesignal generator 101 can still be updated after the signal generator 101is implanted, via a wireless physician's programmer 117 (e.g., aphysician's laptop, physician's remote, etc.) and/or a wireless patientprogrammer 106 (e.g., a patient's laptop, a patient's remote, etc.).Generally, the patient 190 has control over fewer parameters than doesthe practitioner.

FIG. 2 is a partially schematic isometric view of an implantable signalgenerator 200 having a header portion or header 202 and a can 204configured in accordance with an embodiment of the present technology.The can 204 may include a rounded rectangular shell 206 and an ovalshaped lid 208. In one embodiment, the shell 206 and the lid 208 can betitanium, and a weld joint 210 can join the lid 208 to the shell 206. Inother embodiments, the shell 206 and the lid 208 can be made of othermetals or metal alloys, or plastic, and can be joined together by othermethods including press fitting, adhesive materials and/or threadedconnections. In any of these embodiments, the lid 208 can include aplurality of feed-throughs 212 for electrical communication between theheader 202 and the can 204.

The header 202 can include a charging and communication assembly 214, afirst receiving element 216 a and a second receiving element 216 b(collectively, receiving elements 216). The receiving elements 216 caninclude a plurality of output terminals or contact assemblies 218,configured to provide electrical connections to the signal deliverydevice 110 (FIG. 1) or the lead extension 102 (FIG. 1). The charging andcommunication assembly 214 can include a support element 220 carrying acommunication antenna 222 and a charging coil 224. The communicationantenna 222 includes curved connectors 223 (identified individually as afirst curved connector 223 a and a second curved connector 223 b). Thesupport element 220, the communication antenna 222 and the charging coil224 can be shaped, positioned, and/or otherwise configured to enhancethe performance of the implantable signal generator, while fittingwithin the confines of the header 202 as will be described furtherbelow. Multiple wires 226 can extend upwardly from the can 204 throughthe feed-throughs 212 and couple to (a) individual contact assemblies218, (b) the curved connectors 223, and (c) the charging andcommunication assembly 214 via bushings 228 (identified individually asa first bushing 228 a and a second bushing 228 b).

The wires 226 can provide electrical connections between componentswithin the header 202, e.g., the charging coil 224 and the communicationantenna 224, and components within the can 204, e.g., a battery 230, acontroller 232, etc. The battery 230 can be electrically coupled to thecontroller 232 and the output terminals or contact assemblies 218 toprovide electrical power to the implantable signal generator 200 via thereceiving elements 216. The battery 230 can be recharged via anelectrical coupling to the charging coil 224. The controller 232 can beelectrically coupled to the contact assemblies 218 and the battery 230,and can include a processor 234, memory 236, electronic circuitry, andelectronic components for controlling and/or operating the implantablesignal generator. Computer readable instructions contained in the memory236 can include operating parameters and instructions that can controlthe operation of the implantable signal generator 200. In operation, thecharging coil 224 can convert electromagnetic energy (e.g., a magneticflux) into electrical current to charge the battery 230. Thecommunication antenna 224 can receive signals related to operation andcontrol of the implantable signal generator 200. For example, controlsignals to update operating parameters (e.g., the frequency or durationof modulation signals) for the implantable signal generator 200 can bereceived by the communications antenna 224 and sent to the controller232. The controller 232 can control the delivery of electrical power tothe receiving elements 216.

FIG. 3 is an isometric view of a representative charging coil 224 havinga pair of wire loops 302 (identified individually as a first wire loop302 a and a second wire loop 302 b) in accordance with anotherembodiment of the present technology. Each of the wire loops 302 can beformed from a wire 304 (identified individually as a first wire 304 aand a second wire 304 b). The first wire 304 a and the second wire 304 bcan be made from a variety of suitable metals or metal alloys (e.g.,copper, silver coated copper, gold coated copper, gold, silver, platinumand/or other suitable metals or metal alloys). The first wire 304 a hasa first end 306 a and a second end 307 a. Similarly, the second wire 304b has a first end 306 b and a second end 307 b. The first end 306 a ofthe first wire 304 a and the first end 306 b of the second wire 304 bare crimped together at the first bushing 228 a. The second end 307 a ofthe first wire 304 a and the second end 307 b of the second wire 304 bare crimped together at the second bushing 228 b. Accordingly, the twoloops 302 a, 302 b are connected in parallel. Although the illustratedembodiment includes two wires 304, other embodiments can includeadditional wires, and/or filers, and/or multi-filer wires, and/or a Litzwire having individually insulated wires that can be woven or braidedinto a bundle. For example, in one embodiment, one or more wire loopscan include four wires or filers, rather than the two wires 304 shown inthe illustrated embodiment.

The wire loops 302 can be formed by wrapping the first wire 304 a arounda spindle (not shown) multiple times, removing the spindle, wrapping thesecond wire 304 b around a spindle multiple times, removing the spindle,laying the resulting wire loops 302 a and 302 b next to each other, andcoating the wire loops 302 with an insulator 310. In other embodiments,the first wire 304 a and the second wire 304 b can be concurrentlywrapped around the spindle, with the resulting wire loops having thefirst wire 304 a and the second wire 304 b in contact with each otheralong the entire lengths of the wires 304 a, 304 b. In any of theseembodiments, the first ends 306 a, 306 b and the second ends 307 a, 307b can be wrapped around the wire loops 302 to hold the wire loops 302 a,302 b together, and the wire loops 302 can be coupled to the supportelement 220 (FIG. 2), as will be described further below.

Single wire loops that are used for inductive power generation cancreate increased heat due to electromagnetic properties inherent ininductive charging (e.g., the skin effect). By using multiple wires andloops, the skin effect can be reduced, causing a subsequent reduction inheat generation and/or a corresponding increase in the inductivecharging capability. In some embodiments, the charging coil can have aresistance chosen to reduce the skin effect. For example, in oneembodiment, a charging coil can have a resistance in the range of 2 ohmsto 10 ohms. In other embodiments, charging coils can have a resistancethat is greater than 10 ohms or less than 2 ohms. In particularembodiments, the pair of wires 304 may be wrapped around the spindle aspecific number of times to enhance the performance of the charging coil224 based on the size, shape and/or electromagnetic characteristics ofthe implantable signal generator 200 (FIG. 2), the external power source103 (FIG. 1) and/or other components of the patient system 100 (FIG. 1).For example, in one embodiment, each wire 304 may be wrapped around thespindle 30 times. In other embodiments, the wires 304 may be wrappedaround the spindle more or fewer times.

The charging coil 224 can be shaped to provide desired operationalcharacteristics and to fit within the header 202 (FIG. 2). Accordingly,the support element 220 (FIG. 2) can be shaped in a corresponding mannerto support the charging coil 224 and enable a secure coupling betweenthe support element 220 and the charging coil 224. In the illustratedembodiment of FIG. 3, the charging coil 224 has a generally rectangularshape corresponding to the shape of the header 202, and a portion of thesupport element 220 (FIG. 2) corresponds to (e.g., closely matches) thisrectangular shape. In other embodiments, the charging coil 224 and/orthe support element 220 can have other shapes (e.g., circular, square,oval) to enhance the performance and/or fit of the charging coil 224within the header 202 of the implantable signal generator 200 (FIG. 2).

FIG. 4 is an isometric view of a representative communication antenna222 having curved connectors 223 a, 223 b configured in accordance witha further embodiment of the present technology. The communicationantenna 222 can be made from a variety of metals or metal alloys (e.g.,copper, silver coated copper, gold coated copper, gold, silver, platinumand/or other suitable metals or metal alloys). In one embodiment, thecommunication antenna 222 can be made from magnet wire that is bent orotherwise formed into the rounded rectangular shape shown in FIG. 4. Thecommunication antenna 222 can be shaped to provide particularcommunication capabilities and to fit within the implantable signalgenerator 200 (FIG. 2). The support element 220 (FIG. 2) can be shapedto correspond to (e.g., closely match) the shape of the communicationantenna 222, and the curved connectors 223 a, 223 b can wrap around thesupport element 220, as will be described further below. The firstcurved connector 223 a can include a first receiving cavity 404 a andthe second curved connector 223 b can include a second receiving cavity404 b. The first receiving cavity 404 a and the second receiving cavity404 b (collectively, the receiving cavities 404) can each be configuredto individually receive an individual wire 226 (FIG. 2), as will bedescribed further below.

FIG. 5 is an isometric view of the support element 220, illustrating afirst receiving surface 502 and a second receiving surface 504positioned in accordance with an embodiment of the present technology.The first receiving surface 502 can be generally flat and can extendaround the perimeter of the support element 220 in a shape that engagesthe communication antenna 222 (FIG. 4). Similarly, the second receivingsurface 504 can be a generally flat surface and can extend around theperimeter of the support element 220 in a shape that supports thecharging coil 224 (FIG. 3). The support element 220 can be molded fromplastic or formed from other materials and shaped to support thecommunication antenna 222 (FIG. 4) and the charging coil 224 (FIG. 3).For example, the support element 220 can be made from silicone, an epoxy(e.g., epoxies manufactured by Hysol® or EPO-TEK®), Tecothane® and/orDelrin®. Adhesive elements 506 can be added to the first receivingsurface 502 and/or the second receiving surface 504 to secure thecommunication antenna 222 (FIG. 4) and/or the charging coil 224 (FIG.3).

FIG. 6 is an isometric view of a representative charging andcommunication assembly 214 including the communication antenna 222 andthe charging coil 224, configured in accordance with an embodiment ofthe present technology. In the illustrated embodiment, the communicationantenna 222 is engaged with the first receiving surface 502 (FIG. 5) andthe curved connectors 223 a, 223 b are at least partially curved arounda portion of the support element 220. The curved connectors 223 a, 223 bcan be shaped and/or positioned to aid in relieving stress on thefeed-throughs 212 (FIG. 2). The adhesive elements 506 (FIG. 5) aid insecuring the communication antenna 222 and the charging coil 224 to thesupport element 220. Although the illustrated embodiment includes thecharging coil 224 and the communication antenna 222 secured to thesupport element 220 with adhesive elements and/or curved connectors, inother embodiments, other fasteners or features can provide for thisfunction. For example, fastening clips or tabs can be screwed orotherwise fastened to the support element 220 and can engage thecommunication antenna 222 and/or the charging coil 224. The supportelement 220 can be molded or formed to have grooves and/or flexible tabsthat can secure the communication antenna 222 and/or the charging coil224.

Referring to FIG. 2 and FIG. 6 together, the communication antenna 222and the charging coil 224 carried by the support element 220 can becoupled to electrical components within the can 204 by connectingindividual wires 226 to the curved connectors 223 a, 223 b and thebushings 228. The wires 226 that connect to the curved connectors 223 a,223 b can be bent, as shown in FIG. 2, to align with the curvedconnectors 223 a, 223 b. The wires 226 can hold the support element 220and the receiving elements 216 in the position shown in FIG. 2. Theheader 202 (FIG. 2) can undergo further processing to enclose thesupport element 220 and at least a portion of the receiving elements216. For example, the header 202 can be at least partially immersed orencased in epoxy to seal the support element 220, the wires 226, thebushings 228, the charging coil 224, the communication antenna 222 andat least a portion of the receiving elements 216.

FIG. 7 is an isometric view of a portion of the implantable signalgenerator 200 with a header 202 configured in accordance with a furtherembodiment of the present technology. In the illustrated embodiment, theheader 202 includes an epoxy volume 702 having receiving inlets 704(identified individually as a first receiving inlet 704 a and a secondreceiving inlet 704 b). The receiving inlets 704 provide access to thereceiving elements 216 a, 216 b, thus allowing a lead 111 (FIG. 1) or alead extension 102 (FIG. 1) to be connected to the signal generator 200.The epoxy volume 702 and the receiving inlets 704 can be formed in anyof a variety of suitable manners. For example, the epoxy volume 702 andthe receiving inlets 704 can be formed by placing a temporary plug (notshown) in each individual receiving element 216 and immersing the header202 in epoxy (e.g., an epoxy filled mold). In other embodiments, theheader 202 can be encased in other materials, including molded plastic.In some embodiments, the header 202 can be encased using casting and/orpre-molding methods.

Embodiments in accordance with the present technology can includecharging coils and communication antennas shaped and configured in avariety of suitable manners. FIGS. 8A-8D schematically illustratecharging coils configured in accordance with other embodiments of thepresent disclosure. For example, FIG. 8A shows a charging coil 802 ahaving a first wire loop 804 a and a second wire loop 804 b(collectively, wire loops 804) in a side by side, rectangularconfiguration. In the embodiment shown, wire loops 804 a and 804 b havematching sizes and shapes. However, in alternative embodiments, wireloops 804 a and 804 b may differ in size and shape. The size, shape, andlocation of wire loops 804 may be configured to optimize batterycharging parameters. For example, in one embodiment, charging coil 802 ais configured to provide daily charging for an implantable signalgenerator configured to provide high frequency therapy signals (e.g.,therapy signals at a frequency in a frequency range of from about 1.5kHz to about 100 kHz, and current amplitudes in a range of from about0.1 mA to about 20 mA).

FIG. 8B shows a charging coil 802 b having a plurality of wire loops 808(identified individually as a first wire loop 808 a, a second wire loop808 b, a third wire loop 808 c and a fourth wire loop 808 d). In theembodiment shown, wire loops 808 a, 808 b, 808 c, and 808 d havematching sizes and shapes. However, in alternative embodiments, one ormore of wire loops 808 a, 808 b, 808 c, and 808 d may differ in size andshape. The size, shape, and location of wire loops 808 may be configuredto optimize battery charging parameters. For example, in one embodiment,charging coil 802 b is configured to provide daily charging for animplantable signal generator configured to provide high frequencytherapy signals (e.g., therapy signals at a frequency in a frequencyrange of from about 1.5 kHz to about 100 kHz, and current amplitudes ina range of from about 0.1 mA to about 20 mA).

FIG. 8C shows a charging coil 802 c having a first wire loop 810 a and asecond wire loop 810 b (identified collectively as wire loops 810) in anoffset, parallel plane, hemisphere-shaped configuration. The chargingcoil 802 c can include one or more wires 811 that form the wire loops810 and can connect the first wire loop 810 a to the second wire loop810 b. The first wire loop 810 a and the second wire loop 810 b can beoffset along a first axis A1 and along a second axis A2 such that thefirst wire loop 810 is in a first plane, and the second wire loop 810 bis in a second plane, different from the first plane. In the embodimentshown, wire loops 810 a and 810 b have matching sizes and shapes.However, in alternative embodiments, the wire loops 810 a and 801 b maydiffer in size and shape. The size, shape, and location of wire loops810 may be configured to optimize battery charging parameters. Forexample, in one embodiment, charge coil 802 c is configured to providedaily charging for an implantable signal generator configured to providehigh frequency therapy signals (e.g., therapy signals at a frequency ina frequency range of from about 1.5 kHz to about 100 kHz, and currentamplitudes in a range of from about 0.1 mA to about 20 mA).

FIG. 8D shows a charging coil 80 d having six wire loops 812 (identifiedindividually as wire loops 812 a-812 f) arranged in a rectangular cube.In a manner similar to the charging coil 802 c, the charging coil 802 dcan include one or more wires 813 that form the wire loops 812 and canconnect the wire loops 812. The size, shape, and location of wire loops812 a-812 f may be configured to optimize battery charging parameters.For example, in one embodiment, the charging coil 802d is configured toprovide daily charging for an implantable signal generator configured toprovide high frequency therapy signals (e.g., therapy signals at afrequency in a frequency range of from about 1.5 kHz to about 100 kHz,and current amplitudes in a range of from about 0.1 mA to about 20 mA).

The charging coils 802 a-802 d provide improved charging capabilities asa result of the relative positions of the respective wire loops withinan implantable signal generator. For example, the offset position of thewire loops 810 of the charging coil 802 c can allow space for othercomponents while providing a large overall cross-sectional area toincrease the rate at which energy is transferred to the charging coil802 c. Additionally, the six wire loops 812 a-812 f of the charging coil802 d are positioned to face six different directions, and can therebyinteract with magnetic fields directed at the charging coil 802 d fromany of a variety of different directions. Although the charging coils802 a-802 d include wire loops that are in the same plane, in parallelplanes, or in orthogonal planes, charging coils in accordance with thepresent technology can include wire loops that are positioned in planesat a variety of suitable non-zero angles. Additionally, the chargingcoils 802 a-802 d can include more or fewer wire loops 804, 808, 810 and812 in a variety of shapes and sizes (e.g., circular, oval, square). Inone embodiment, charging coils 802 a, 802 b, 802 c, 802 d, orequivalents thereof, are sized, shaped, located within an implantablesignal generator header, and/or otherwise configured to provide meansfor charging a battery of an implantable signal generator to provide atleast 12 operational hours (and preferably at least 24 operationalhours) in the delivery of high frequency therapy signals at a frequencyin a frequency range of from about 1.5 kHz to about 100 kHz, and currentamplitudes in a range of from about 0.1 mA to about 20 mA.

For example, FIG. 9 is a partially cutaway side view of a portion of animplantable signal generator 900 for delivering therapy signals, with aheader 902 configured in accordance with an embodiment of the presenttechnology. In the illustrated embodiment, a charging coil 924, asupport element 920, and a pair of receiving elements 916 (identifiedindividually as a first receiving element 916 a and a second receivingelement 916 b) are positioned within a header cap 904. The header cap904 can be formed from any of a variety of suitable materials. Forexample, in some embodiments, the header cap 904 can be formed fromepoxy in a manner at least generally similar to that described abovewith respect to FIG. 7. In other embodiments, the header cap 904 can bepre-formed from Tecothane®, East-Eon™, silicone, and/or any othersuitable material and can be attached to the can 204 to encompass thecomponents within the header 902.

The receiving elements 916 can be positioned within the header 902 suchthat the receiving elements 916 are at least generally flush with acurved upper surface 926 of the header 902. For example, because therespective receiving elements 916 a, 916 b are positioned at differentlocations with respect to the curvature of the surface 926, the firstreceiving element 916 a is offset from the second receiving element 916b, such that the receiving elements 916 align with the curved surface926. In some embodiments, the charging coil 924 can be shaped to atleast partially match the shape of the header 902. For example, in theillustrated embodiment, the charging coil 902 includes a hemispheric or“D” shape that closely matches the shape of the header 902. Matching theshape of the charging coil 924 to the shape of the header 902 increasesthe cross-sectional area of the charging coil 924 and increase thecharging performance, thereby facilitating the battery charging forhigh-demand implantable signal generators, such as signal generatorsconfigured to deliver high frequency therapy.

The header 902 includes a first access seal 917 a and a second accessseal 917 b (collectively referred to as the access seals 917). Theaccess seals 917 include a self-sealing entrance point to provide accessfor a tool (e.g., a screwdriver) to secure a connection (e.g., a screw)to the signal delivery device 110 (FIG. 1) or the lead extension 102(FIG. 1). The access seals 917 can be formed from a pliable silicone orother suitable material such that the tool can pass through and expandthe entrance point. When the tool is withdrawn, the entrance point canautomatically close to reduce or eliminate the possibility of anysubsequent entrance of foreign material (e.g., blood or other bodilyfluids) into the header 902.

FIG. 10 is a cross-sectional end view of a portion of the implantablesignal generator 900 configured in accordance with an embodiment of thepresent technology. In the illustrated embodiment, the support element920 is attached to the lid 208 and carries the charging coil 924.Similar to the support element 220, the support element 920 can be madefrom variety of suitable materials (e.g., silicone, an epoxy (e.g.,epoxies manufactured by Hysol® or EPO-TEK®), Tecothane® and/or Delrin®).The receiving elements 916 and an antenna (not shown) can be attached tothe support element 920. The support element 920 can maintain theposition of the charging coil 924, the antenna, and/or the receivingelements 916 while the header cap 904 is formed and/or positioned on theimplantable signal generator 900.

FIGS. 11A and 11B are isometric views of implantable signal generators1100 a and 1100 b, respectively, configured in accordance withembodiments of the present technology. The implantable signal generator1100 a of FIG. 11A includes a unitary header cap 1002. The implantablesignal generator 1100 b of FIG. 11B includes a two-piece header cap 1102having a first portion 1104 and a second portion 1106. Similar to theheader cap 904, the header caps 1002 and 1104 can be formed from epoxyor can be pre-formed from Tecothane®, Elast-Eon™, silicone or othermaterials. The header caps 1002 and 1104 can be attached to the can 204in a variety of suitable manners. For example, in one embodiment, theheader caps 1002, 1102 can be attached to the lid 208 (not visible inFIGS. 11A and 11B) with an adhesive. In other embodiments, the lid 208,the can 204 and/or other components can include a groove and the headercap 1102 can include a ring that can engage the groove.

FIG. 12 is an isometric view of a pre-molded header cap 1202 configuredin accordance with an embodiment of the present technology. In theillustrated embodiment, the header cap 1202 includes a plurality ofcutouts or openings 1204. The openings 1204 can be shaped to accommodatevarious components that can be positioned within the header cap 1202(e.g., receiving elements, charging coils, antennae, etc.). In someembodiments, components can be inserted into the header cap 1202 and theheader cap 1202 can maintain the components in a desired position duringsubsequent attachment to the can 204.

Although the charging coils and communication antennas discussed abovehave been described as separate components, in other embodiments thefunctions provided by these components can be performed by the sameelement or elements. For example, both the charging and communicationscan be performed by the same coil/antenna, e.g., if the frequency usedto charge and communicate signals is the same, approximately the same,generally similar or otherwise compatible. The coil/antenna can includea single loop or multiple loops, as described above.

One feature of at least some of the foregoing embodiments is that thecharging coils and the communications antennae are positioned in theheaders. An additional advantage of this feature is that it can reducethe manufacturing complexity and the associated cost of producing theimplantable signal generator. For example, the charging coils ofexisting signal generators are often located in a compartment (e.g., acontainer or pouch) coupled to an external surface of the can. Having anexternal compartment necessitates additional fabrication and processingsteps to form the compartment and requires additional electricalconnections between the compartment and the header and/or additionalpenetrations through the side of the can to accommodate electricalconnections. In embodiments of the present disclosure, the header canhouse all of the permanent electrical connections that are external tothe can, and all of the external components can be encased in oneoperation (e.g., forming the epoxy volume or attaching the header cap).Accordingly, implantable signal generators in accordance withembodiments of the present technology can provide several advantagesover existing devices.

In some embodiments, the charging coil has an operational range of threeto four centimeters. Accordingly, the charging coil can be separatedfrom the external power source by up to three to four centimeters duringcharging. The communications antenna can have an operational range of 60centimeters or more, facilitating transmission between thecommunications antenna and the wireless physician's programmer and/orthe wireless patient programmer within this range. Accordingly, theimplantable signal generator can be implanted with the charging coillocated closer to the patients skin than is the communications antenna,to accommodate the shorter operational range of the charging coil. Insome embodiments, this configuration can enhance (e.g., optimize) thecharging capability of the implantable signal generator. In otherembodiments, the implantable signal generator can be implanted with thecharging coil more distal from the patients skin relative to thecommunications antenna.

Regardless of the location within a patient, the implantable signalgenerators described herein provide enhanced charging and communicationcapabilities over other devices. For example, the location of thecharging coil within the header reduces interference or attenuation thatcan occur with charging coils that are located within the can orattached to the can. For example, electromagnetic signals from anexternal power source that are directed to the charging coil are lesslikely to be inadvertently absorbed by the can. Locating the chargingcoil in the header can also reduce the heat generated by theelectromagnetic induction of the charging process. For example, theexternal power source can be positioned primarily over the header, andnot the can, so that the amount of energy generated by the externalpower source and absorbed by the can may be reduced, thereby reducingunwanted induction and heat generation in the can.

In addition to or in lieu of the above advantages, the reducedinterference and enhanced charging and communication capabilities ofdevices in accordance with the present technology can provide greaterflexibility for the practitioner who positions the implantable signalgenerator within a patient. Existing signal generators often require thecharging coil to be positioned proximal to a patient's skin relative toother components. For example, signal generators having charging coilslocated in a compartment on the external surface of the can generallyhave to be implanted with the compartment facing the patient's skin.This limitation can reduce the ability of a practitioner to position thesignal generator to optimize connections to other components. Forexample, the practitioner may have to route leads or other electricalconnections a further distance because the signal generator cannot be“flipped” to provide connections on the preferred side of animplantation site. In several of the embodiments of the presenttechnology, a practitioner can position the implantable signal generatorwith the receiving inlets facing a chosen direction, without regard forthe relative proximity of the charging coil or the communicationsantenna to the patient's skin. Accordingly, the reduced interference andenhanced charging capabilities of the present technology provide forgreater implantation options.

In addition to the advantages discussed above, implantable signalgenerators and/or charging coils in accordance with the presenttechnology can be particularly beneficial for systems employing highfrequency modulation. For example, the signals and operationalparameters of high frequency systems can require greater power usagethan traditional SCS systems. The increased charging efficiency of thepresent technology can help meet greater power requirements withoutnecessitating longer charge times. Accordingly, several embodiments inaccordance with the present technology can be combined with highfrequency modulation systems, including those described in U.S. patentapplication Ser. No. 12/264,836, filed Nov. 4, 2008, and titledMULTI-FREQUENCY NEURAL TREATMENTS AND ASSOCIATED SYSTEMS AND METHODS;U.S. patent application Ser. No. 12/765,747, filed Apr. 22, 2010, andtitled SELECTIVE HIGH-FREQUENCY SPINAL CORD MODULATION FOR INHIBITINGPAIN WITH REDUCED SIDE EFFECTS AND ASSOCIATED SYSTEMS AND METHODS; andU.S. patent application Ser. No. 13/607,617, filed Sep. 7, 2012, andtitled SELECTIVE HIGH FREQUENCY SPINAL CORD MODULATION FOR INHIBITINGPAIN, INCLUDING CEPHALIC AND/OR TOTAL BODY PAIN WITH REDUCED SIDEEFFECTS, AND ASSOCIATED SYSTEMS AND METHODS. The above referenced patentapplications are incorporated herein by reference in their entireties.

Furthermore, several features of the embodiments described herein canprovide additional synergistic effects in systems employing highfrequency modulation. For example, four wire charging coils, copperalloy charging coils, the position of the charging coil and/or theantenna within a header of an implantable signal generator, and/or otherfeatures can provide synergistic affects for systems delivering highfrequency signals for neural modulation.

From the foregoing, it will be appreciated that specific embodiments ofthe disclosed technology have been described herein for purposes ofillustration, but that various modifications may be made withoutdeviating from the technology. For example, rather than a single supportelement having external surfaces that support both the charging coil andthe communication antenna, the charging coil and the communicationantenna can be supported by individual structures having differentshapes or configurations. In other embodiments, the charging coil andthe communication antenna can be supported solely by wires extendingfrom the can of the implantable signal generator, without a supportelement. Other materials may be used in place of those described herein,or additional components may be added or removed. For example, althoughthe illustrated embodiments include a header having two receivingelements, other embodiments can include additional receiving elements,or other connectors. Additionally, any of the embodiments shown ordescribed herein may be combined with each other as the context permits.

Additional Embodiments

In one embodiment, there is provided an implantable signal generator,comprising: (a) a can having an output terminal and a batteryelectrically coupled to the output terminal; and (b) a header portionadjacent the can and having a communication antenna, and a charging coilelectrically coupled to the battery, wherein the charging coil ispositioned to receive electromagnetic energy and direct electricalcurrent to charge the battery, and wherein the communication antenna ispositioned to receive external control signals. The implantable signalgenerator may further comprise: (c) a support element positioned in theheader, wherein the charging coil and the communication antenna areconnected to the support element. The charging coil may include aplurality of wire loops. A first wire loop may be positioned in a firstplane and a second wire loop is positioned in a second plane, andwherein the second plane is different from the first plane.Alternatively, a first wire loop is positioned in a first plane and asecond wire loop is positioned in a second plane, the first planedisposed at a non-zero angle with respect to the second plane.

The header portion may include: (i) a plurality of receiving elementspositioned to provide electrical connections; and (ii) an epoxy volumeat least partially encasing the receiving elements. The header mayalternatively include a curved surface, and wherein the charging coil isshaped to at least partially match the curved surface.

The can may include a shell and a lid, the lid having a plurality offeed-throughs. The implantable signal generator may thus furthercomprise: a controller positioned within the can and configured todirect electrical signals to the output terminal; and a plurality ofwires positioned to extend through the feed-throughs and operably couplethe controller to the communication antenna and the battery to thecharging coil.

In another embodiment, there is provided an implantable medical devicefor delivering electrical therapy signals to a patient's spinal regionto alleviate pain. The medical device comprising: (a) a can having ashell and a lid, wherein the lid includes a plurality of feed-throughs;(b) an output terminal positioned to provide electrical power to asignal delivery device; (c) a controller disposed within the can andcoupled to the output terminal to control electrical power directed tothe output terminal; (d) a battery disposed within the can and coupledto the controller; (e) a plurality of wires, individual wires extendingupwardly from the can through corresponding individual feed-throughs;(f) a header carried by the can; (g) a support element disposed withinthe header; (h) a charging coil having at least one wire loop, thecharging coil being carried by the support element in the header suchthat the entirety of the wire loop is disposed outside of the can, andwherein the charging coil is operably coupled to the battery via atleast one first individual wire; and (i) a communication antenna carriedby the support element and operably coupled to the controller via atleast one second individual wire. The charging coil may include aplurality of wire loops, wherein a first wire loop is offset from asecond wire loop along both a first axis and a second axis orthogonal tothe first axis. The charging coil may otherwise include a plurality ofwire loops, wherein a first wire loop is positioned in a first plane anda second wire loop is positioned in a second plane, the first planedisposed at a non-zero angle relative to the second plane. The headermay include a curved surface, wherein the charging coil is shaped to atleast partially match the shape of the curved surface.

The medical device may further comprise a receiving element disposed inthe header, wherein the header includes an epoxy volume and thereceiving element is at least partially encased in the epoxy volume, thereceiving element including the output terminal. The medical device mayfurther comprise a header cap, wherein the support element is attachedto the lid and configured to support the charging coil and thecommunication antenna.

In yet another embodiment, there is provided a method for forming animplantable signal generator, comprising: (a) forming a shell; (b)forming a lid having a plurality of feed-throughs; (c) attaching the lidto the shell; (d) forming a charging coil; (e) forming a communicationantenna; and (f) positioning the communication antenna and the chargingcoil to be supported by the lid, external to the shell. The method mayfurther comprise: (g) positioning a battery and a controller within theshell; (h) electrically coupling the charging coil to the battery; and(i) electrically coupling the communication antenna to the controller.The method may further comprise forming a header cap to encase thecharging coil and the communication antenna. Forming the charging coilmay include forming a plurality of wire loops, and wherein the methodfurther may further comprise positioning a first wire loop in a firstplane and positioning a second wire loop in a second plane, the firstplane is disposed at a non-zero angle relative to the second plane.Alternatively, the method may further comprise forming a supportelement, wherein positioning the communication antenna and the chargingcoil to be supported by the lid includes attaching the communicationantenna and the charging coil to the support element. The method mayfurther comprise forming a header cap having a curved surface.

In still another embodiment, there is provided a spinal cord stimulationsystem for applying therapy signals to a patient's spinal region. Thesystem comprising: an implantable signal generator having (a) a can (orhousing) having an output terminal and a battery (disposed within thehousing) electrically coupled to the output terminal; and (b) a headerportion adjacent the can and having a communication antenna, and acharging coil electrically coupled to the battery. The charging coil ispositioned (e.g., within the header portion outside of the can (orhousing)) to receive electromagnetic energy (e.g., from an externalpower source) and direct electrical current to charge the battery. Thecommunication antenna may be positioned (e.g., within the header portionoutside of the can (or housing)) to receive external control signals.The implantable signal generator may further comprise: (c) a supportelement positioned in the header, wherein the charging coil and thecommunication antenna are connected to the support element. The chargingcoil may include a plurality of wire loops. A first wire loop may bepositioned in a first plane and a second wire loop is positioned in asecond plane, and wherein the second plane is different from the firstplane. Alternatively, a first wire loop is positioned in a first planeand a second wire loop is positioned in a second plane, the first planedisposed at a non-zero angle with respect to the second plane.

The system further comprises at least one lead body connected to theimplantable signal generator and having at least one electrode. In oneembodiment, the implantable signal generator generates a high frequencytherapy signal having a frequency in the range of from about 1,500 Hz toabout 100,000 Hz for delivery through the lead body electrode. The highfrequency range may alternatively be from about 2,500 Hz to about 20,000Hz; or from about 3,000 Hz to about 10,000 Hz. The high frequencytherapy signal may be biphasic, may be a sine wave or a square wave,and/or may be applied at a duty cycle of about 50% or less. The highfrequency therapy signal may have a current amplitude in an amplituderange from about 0.1 mA to about 20 mA. The high frequency therapysignal may be applied in place of a low frequency stimulation signal toreplace pain relief provided by paresthesia. In other words, the highfrequency therapy signal may be applied to the patient's spinal cordregion to alleviate pain without causing the patient to experienceparesthesia. The implantable signal generator may generate the highfrequency therapy signal for application directly to the dorsal column,the dorsal root, and/or the dorsal root ganglion. The implantable signalgenerator may be configured to adjust the high frequency therapy signalsuch that after the high frequency therapy signal has been initialized,an amplitude of the high frequency therapy signal is reduced from afirst operating level to a second, lower operating level withoutaffecting the sensory experience of the patient. For example, theamplitude of the high frequency therapy signal may be reduced by about10-30% after initialization. The implantable signal generator may alsobe configured to apply the high frequency therapy signal in adiscontinuous fashion so as to include periods when the high frequencytherapy signal is applied, and periods when the high frequency therapysignal is terminated according to a duty cycle. The implantable signalgenerator may also be configured to generate a low frequency therapysignal to selectively induce paresthesia, wherein the low frequencytherapy signal has a frequency in the range of up to about 1,500 Hz.

In one embodiment, one or more of the above-described headers areprovided in a hemispherical (or sideways “D”) shape attached to the topof the signal generator's can (or housing). The charge coil within theheader is then configured to have a shape that at least partiallyfollows (or matches) the shape of the header. As such, a hemisphericallyshaped header is matched with a hemispherically shaped charging coil.

In yet another embodiment, an implantable medical device includes a canhaving a shell and a lid, wherein the lid includes a plurality offeed-throughs. An output terminal can be positioned to provideelectrical power to a signal delivery device and a controller can bepositioned within the can and coupled to the output terminal to controlelectrical power directed to the output terminal. A battery disposedwithin the can can be coupled to the controller and a plurality of wirescan extend upwardly from the can through corresponding individualfeed-throughs. A header having a curved surface can be carried by thecan and a support element can be positioned within the header. Acharging coil having at least one wire loop can include four individualwires or filers. The wires or filers can include at least two of a)copper, b) silver, and c) gold. The charging coil can be carried by thesupport element in the header such that the entirety of the wire loop isdisposed outside of the can, and the charging coil can be operablycoupled to the battery via at least one first individual wire. Thecharging coil can have a resistance within the range of 2 ohms to 12ohms, and a communication antenna can carried by the support element andoperably coupled to the controller via at least one second individualwire.

While various advantages and features associated with certainembodiments have been described above in the context of thoseembodiments, other embodiments may also exhibit such advantages and/orfeatures, and not all embodiments need necessarily exhibit suchadvantages and/or features to fall within the scope of the technology.Accordingly, the disclosure and associated technology can encompassother embodiments not expressly shown or described herein.

I/we claim:
 1. An implantable medical device for delivering electricaltherapy signals to a patient's spinal region to alleviate pain,comprising: a can having a shell and a lid, wherein the lid includes aplurality of feed-throughs; an output terminal positioned to provideelectrical power to a signal delivery device; a controller disposedwithin the can and coupled to the output terminal to control electricalpower directed to the output terminal; a battery disposed within the canand coupled to the controller; a plurality of wires, individual wiresextending upwardly from the can through corresponding individualfeed-throughs; a header carried by the can; a support element disposedwithin the header; a charging coil having at least one wire loop, thecharging coil being carried by the support element in the header suchthat the entirety of the wire loop is disposed outside of the can, andwherein the charging coil is operably coupled to the battery via atleast one first individual wire; and a communication antenna carried bythe support element and operably coupled to the controller via at leastone second individual wire.
 2. The medical device of claim 1, whereinthe charging coil includes a plurality of wire loops, and wherein afirst wire loop is offset from a second wire loop along both a firstaxis and a second axis orthogonal to the first axis.
 3. The medicaldevice of claim 1, wherein the charging coil includes a plurality ofwire loops, and wherein a first wire loop is positioned in a first planeand a second wire loop is positioned in a second plane, the first planedisposed at a non-zero angle relative to the second plane.
 4. Themedical device of claim 1, further comprising a receiving elementdisposed in the header, wherein the header includes an epoxy volume andthe receiving element is at least partially encased in the epoxy volume,the receiving element including the output terminal.
 5. The medicaldevice of claim 1, wherein the header includes a curved surface, andwherein the charging coil is shaped to at least partially match theshape of the curved surface.
 6. The medical device of claim 1, furthercomprising a header cap, wherein the support element is attached to thelid and configured to support the charging coil and the communicationantenna.
 7. An implantable signal generator, comprising: a can having anoutput terminal and a battery electrically coupled to the outputterminal; and a header portion adjacent the can and having acommunication antenna, and a charging coil electrically coupled to thebattery, wherein the charging coil is positioned to receiveelectromagnetic energy and direct electrical current to charge thebattery, and wherein the communication antenna is positioned to receiveexternal control signals.
 8. The implantable signal generator of claim7, further comprising a support element positioned in the header,wherein the charging coil and the communication antenna are connected tothe support element.
 9. The implantable signal generator of claim 7,wherein the charging coil includes a plurality of wire loops.
 10. Theimplantable signal generator of claim 9, wherein a first wire loop ispositioned in a first plane and a second wire loop is positioned in asecond plane, and wherein the second plane is different from the firstplane.
 11. The implantable signal generator of claim 9, wherein a firstwire loop is positioned in a first plane and a second wire loop ispositioned in a second plane, the first plane disposed at a non-zeroangle with respect to the second plane.
 12. The implantable signalgenerator of claim 7, wherein the header portion includes: a pluralityof receiving elements positioned to provide electrical connections; andan epoxy volume at least partially encasing the receiving elements. 13.The implantable signal generator of claim 7, wherein the header includesa curved surface, and wherein the charging coil is shaped to at leastpartially match the curved surface.
 14. The implantable signal generatorof claim 7, wherein the can includes a shell and a lid, the lid having aplurality of feed-throughs, and wherein the implantable signal generatorfurther comprises: a controller positioned within the can and configuredto direct electrical signals to the output terminal; and a plurality ofwires positioned to extend through the feed-throughs and operably couplethe controller to the communication antenna and the battery to thecharging coil.
 15. A method for forming an implantable signal generator,the method comprising: forming a shell; forming a lid having a pluralityof feed-throughs; attaching the lid to the shell; forming a chargingcoil; forming a communication antenna; and positioning the communicationantenna and the charging coil to be supported by the lid, external tothe shell.
 16. The method of claim 15, further comprising: positioning abattery and a controller within the shell; electrically coupling thecharging coil to the battery; and electrically coupling thecommunication antenna to the controller.
 17. The method of claim 15,further comprising: forming a header cap to encase the charging coil andthe communication antenna.
 18. The method of claim 15, wherein formingthe charging coil includes forming a plurality of wire loops, andwherein the method further comprises positioning a first wire loop in afirst plane and positioning a second wire loop in a second plane, thefirst plane is disposed at a non-zero angle relative to the secondplane.
 19. The method of claim 15, further comprising: forming a supportelement, wherein positioning the communication antenna and the chargingcoil to be supported by the lid includes attaching the communicationantenna and the charging coil to the support element.
 20. The method ofclaim 15, further comprising: forming a header cap having a curvedsurface.
 21. An implantable medical device for delivering electricaltherapy signals to a patient's spinal region to alleviate pain,comprising: a can having a shell and a lid, wherein the lid includes aplurality of feed-throughs; an output terminal positioned to provideelectrical power to a signal delivery device; a controller disposedwithin the can and coupled to the output terminal to control electricalpower directed to the output terminal; a battery disposed within the canand coupled to the controller; a plurality of wires, individual wiresextending upwardly from the can through corresponding individualfeed-throughs; a header carried by the can and having a curved surface;a support element disposed within the header; a charging coil having atleast one wire loop, wherein the wire loop includes four individualwires, the individual wires including at least two of a) copper, b)silver, and c) gold, wherein the charging coil is carried by the supportelement in the header such that the entirety of the wire loop isdisposed outside of the can, wherein the charging coil is operablycoupled to the battery via at least one first individual wire, andwherein the charging coil has a resistance within the range of 2 ohms to12 ohms; and a communication antenna carried by the support element andoperably coupled to the controller via at least one second individualwire.